I had the same issue, with the "Catalog Metadata Updates" stuck and not advancing for days.
PM.log mentioned:
AppUtilsCommon.cpp:717 AppUtils::HandleTimerCallback: STARVING
and dyn.log mentioned:
CILA::PROTO::RPCClientConn - do_rpc_dispatch: no_handler
...
DYN: CBits::AM::CatalogMetadataUpdateTask.try_spawn_metadata_update: apply_change_journal_batch failed: [:rpc_timeout]
...
CILA::FiberPool - fiber outer exception: apply_change_journal_batch failed: [:rpc_timeout]
...
CatSvc: CBits::LOCALSVC::CatalogSVC - received error at root: ["no_handler", true]
I just upgraded to the latest Beta 4 R3215 and my finally "Catalog Metadata Updates" finished in less than 10 minutes!
The only new entries left in dyn.log are:
[WARN] DYN: CILA::APPSVC::GUI::Expander dispatch_event: no handler for event "expander_toggle" on component id 546
[WARN] CatSvc: CBits::AM::DB::CatalogDB - ArgumentError: invalid date location=
./archive/common/localsvc/camerabits_catalog/model.rb:3451:in `parse',
./archive/common/localsvc/camerabits_catalog/model.rb:3451:in `block in parse_and_fetch_timestamp_components',
/Applications/Photo Mechanic Plus.app/Contents/pmruby/lib/ruby/site_ruby/2.2.0/cila/noraise.rb:24:in `noraise',
./archive/common/localsvc/camerabits_catalog/model.rb:3450:in `parse_and_fetch_timestamp_components',
./archive/common/localsvc/camerabits_catalog/model.rb:3020:in `insert_or_update_search'